Jen Raaf receives award to build gaseous argon prototype

Jen Raaf works on the readout plane of a neutrino detector. Photo: Reidar Hahn
Jen Raaf works on the readout plane of a neutrino detector. Photo: Reidar Hahn
Jen Raaf works on the readout plane of a neutrino detector. Photo: Reidar Hahn

(Excerpted from article in Fermilab News, 4 May 2106 “Fermilab scientists Sam Posen, Jen Raaf win prestigious DOE Early Career Research Awards)

On May 3 the Department of Energy announced that DUNE collaborator Jen Raaf is a recipient of the prestigious DOE Early Career Research Award.

She will receive $2.5 million, distributed over five years, to fund the construction of a detector that could help scientists better distinguish multiple, nearly simultaneous neutrino interactions from one another. It will also allow better visualization of neutrino interactions…

Liquid-argon time projection chambers take exquisitely detailed three-dimensional images of particle interactions. But for an extremely intense neutrino beam, liquid argon might not cut it.

That’s because electrons drift through liquid argon relatively slowly. If neutrinos interact with argon at a rate faster than the wires can capture them — that is, faster than the time it takes for electrons to drift to the wires — multiple interactions could become indistinguishable. Scientists call this complication “pileup.”

Particles drifting through gaseous argon under high pressure, on the other hand, move much more quickly. So when neutrinos pour in, and two or more interact with gaseous argon in super-rapid succession, they won’t pile up on their way to the charged wires.

“You can better distinguish multiple events arriving close in time than you would in a liquid detector,” Raaf said. “So if you can make it easier for yourself to reconstruct the events, why not do that?”

Gaseous-argon detectors also afford scientists a more detailed look at what happens when a neutrino interacts with a nucleus. Because gaseous argon is less dense than liquid argon, low-energy particles resulting from the neutrino interaction travel farther, leaving behind a longer, more informative track.

If tests are successful, not only would scientists use the detector to explore neutrino-nucleus interactions, but it could also be put forward as a candidate for the DUNE near detector, which will be built at Fermilab close to the neutrino source…

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